They are not hotlinking you, just checked it out. They are just going straight to your gallery folder where you have no index.html, it lists all you pics.
just add this to your htaccess.
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^
http://(www\.)?domain.com/.*$ [NC]
RewriteCond %{HTTP_REFERER} !^
http://i.p number here/.*$ [NC]
RewriteRule \.(gif|jpg)$
http://www.domain.com/index.shtml [R,L]
IndexIgnore *
make sure you put in indexignore * so you don't get this anymore.
http://back-off-bitch.net/gal/ftv/isabella/images/